Access Gate Research Articles

Design analysis of a low-power, high-speed 8 T SRAM cell using dual-threshold CNTFETs

Recently, carbon nanotube field-effect transistors (CNTFETs) have garnered significant attention from VLSI engineers due to their exceptional electrical properties. This paper proposes a novel high-speed, low-power eight-transistor (8 T) static random-access memory (SRAM) cell based on 32-nm CNTFET technology. The SRAM cell was simulated using the HSPICE tool with a VDD of 0.9 V. The high-speed and low-power characteristics of the SRAM design are attributed to the high subthreshold slope and high carrier mobility of metal-oxide-semiconductor field-effect transistor (MOSFET)-like CNTFETs utilized in the simulations. The implementation of dual threshold transistors, coupled with a transmission gate for bitline access, contributes to the enhanced performance. Key performance metrics such as noise margins, power consumption, delay, and SRAM electrical quality metric (SEQM) of the proposed SRAM have been evaluated and compared with existing CNTFET-based SRAM designs. The proposed cell demonstrates reductions of 73.73%, 43.18%, and 58.70% in read power, write power, and hold power, respectively, compared to the lowest respective power values of other examined SRAM designs. The proposed SRAM ranks second, third, and second in write static noise margin (WSNM), hold static noise margin (HSNM), and read static noise margin (RSNM), respectively, among other designs. Additionally, the proposed SRAM exhibits the least sensitivity to parametric variations compared to other designs. The SEQM, which provides a comprehensive assessment of access times, noise margins, and power usage for the SRAM cell, has been calculated. The SEQM of the proposed SRAM is 10.6, 1.89, 13.15, and 1.82 times higher than that of C6T, BLP8T, Mani’s 10 T, and LP8T, respectively.

Stabilizing perpendicular magnetic anisotropy with strong exchange bias in PtMn/Co by magneto-ionics

Electric field control of magnetic properties offers a broad and promising toolbox for enabling ultra-low power electronics. A key challenge with high technological relevance is to master the interplay between the magnetic anisotropy of a ferromagnet and the exchange coupling to an adjacent antiferromagnet. Here, we demonstrate that magneto-ionic gating can be used to achieve a very stable out-of-plane (OOP) oriented magnetization with strong exchange bias in samples with as-deposited preferred in-plane (IP) magnetization. We show that the perpendicular interfacial anisotropy can be increased by more than a factor 2 in the stack Ta/Pt/PtMn/Co/HfO2 by applying −2.5 V gate voltage over 3 nm HfO2, causing a reorientation of the magnetization from IP to OOP with a strong OOP exchange bias of more than 50 mT. Comparing two thicknesses of PtMn, we identify a notable trade-off: while thicker PtMn yields a significantly larger exchange bias, it also results in a slower response to ionic liquid gating within the accessible gate voltage window. These results pave the way for post-deposition electrical tailoring of magnetic anisotropy and exchange bias in samples requiring significant exchange bias.

Port Access Fluidity Management during a Major Extension Project: A Simulation-Based Case Study

The increasing demand for freight services and the use of larger vessels to meet this demand has led to challenges related to storage space and logistics activities, highlighting the need for improvements in port infrastructure for better logistics management. At a crucial phase in its growth, the Port of Trois-Rivières in Canada is planning a major expansion, including the construction of a new terminal to enhance its hosting capacities and freight services. This expansion faces potential access congestion problems during the planned construction, exacerbated by the port’s urban setting. In response to the needs identified by the port authorities for this event, the study’s objective is to assess the implications of increased construction and freight truck flows on access gate fluidity and the impact of additional access infrastructure investment to mitigate potential congestion. These evaluations aim to define effective access management strategies throughout the construction period of the new terminal. To address these complexities, our approach is based on scenario analysis in variants co-constructed with the partner. These scenarios are evaluated using simulation models, configured according to parameters calibrated with a granularity that allows congestion detection. The results enabled an evaluation of the capability of existing and potential gates to manage access. Subsequently, recommendations were shaped in accordance with the expected objectives to manage access traffic effectively. These recommendations concern the optimization of construction activity planning, the layout and planning of access, and the importance of enhanced collaboration between municipal and port authorities for more controlled road traffic management. Recognizing the importance of synchromodality, road network centrality management, and the outsourcing of capacity through inter-port cooperation and with dry ports to manage congestion, these tools will be discussed in this work. The study proposes an approach that reconciles scientific rigor with the implementation constraints of the proposed solutions, allowing this study wider applicability in various port contexts facing challenges in this field of study.

Impact of Spread Effect on Public Market Place (Lambaro Aceh Besar)

Aceh Besar Regency is the primary access and entrance gate to the provincial capital, directly adjacent to the city of Banda Aceh. This proximity positions Aceh Besar as a buffer from the city. The strategic location and position make Aceh Besar an opportune area for rapid growth and development. Thus, developing these strategic areas will foster the emergence of growth centers (Growth Poles). This research aims to determine and analyze the impact of the spread effect on the public market between Aceh Besar Regency and Banda Aceh City as a potential sector that can encourage economic growth and have a spreading effect on the surrounding area. The analysis method employed in this research is a quantitative approach utilizing descriptive analysis. The results of the research show that the results of the gravity analysis of sub-districts in Aceh Besar Regency and Banda Aceh City show that Want Jaya Sub-district as the primary growth center has the greatest interaction value with Darul Imarah Sub-district. The last sub-district is one of the sub-districts in Aceh Besar Regency with an interaction value of 76,525,776,000. Furthermore, the largest interaction values after Darul Imarah District are Krueng Barona Jaya District and Montasik District with interaction values of 15,062,514,047 and 11,831,506,347 respectively.

Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene

The realization of graphene gapped states with large on/off ratios over wide doping ranges remains challenging. Here, we investigate heterostructures based on Bernal-stacked bilayer graphene (BLG) atop few-layered CrOCl, exhibiting an over-1-GΩ-resistance insulating state in a widely accessible gate voltage range. The insulating state could be switched into a metallic state with an on/off ratio up to 107 by applying an in-plane electric field, heating, or gating. We tentatively associate the observed behavior to the formation of a surface state in CrOCl under vertical electric fields, promoting electron–electron (e–e) interactions in BLG via long-range Coulomb coupling. Consequently, at the charge neutrality point, a crossover from single particle insulating behavior to an unconventional correlated insulator is enabled, below an onset temperature. We demonstrate the application of the insulating state for the realization of a logic inverter operating at low temperatures. Our findings pave the way for future engineering of quantum electronic states based on interfacial charge coupling.

16-Bit (4 × 4) Optical Random Access Memory (RAM) Bank

During the past years, the limited access-times and memory bandwidth in electronic random-access memory (RAM) has triggered a concerted research effort towards deploying optical memory circuitry for exploiting the inherent high-bandwidth characteristics of light-based technologies. Yet the deployment of optical memory elements in functional optical RAM demonstrations has still been limited to single-bit capacity levels, with the few multi-bit demonstrations still offering only storage functionality without any true random-access capabilities. In this article, we demonstrate an experimental 16-bit all-optical RAM bank prototype that follows a 4 × 4 matrix organization and supports addressable random access storage of four 4-bit WDM-formatted optical Data Words at a 20 Gb/s memory-throughput. The proposed architecture constitutes of completely passive Row/Column decoding (RD/CD) subsystems, four Semiconductor Optical Amplifier Mach-Zehnder Interferometer (SOA-MZI) Access Gates (AGs) for enabling the access towards the 4 available Word Lines (WLs) and 16 all-optical Flip-Flops (AOFF) arranged in a 4 × 4 RAM bank. Each FF is incorporated in an indicative photonic integrated circuit (PIC). The experimental validation of the complete 16-bit RAM bank reveals error-free operation in Write mode with a peak power penalty between 8.3–10.2 dB at 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> bit-error-rate (BER) measurements, indicating a roadmap for two-dimensional addressable (2D) RAM banks that can penetrate the optical computing application domain.

An All-Optical Address Look-Up Table Using Optical CAM and Optical RAM Banks

We report for the first time, to the best of our knowledge, the experimental demonstration of a complete all-optical 2-bit Address Look-Up (AL) table that performs address matching and forwarding and operates at 10Gb/s. The circuit incorporates an optical Content Addressable Memory (CAM) and an optical Random Access Memory (RAM) table that are interconnected via an optical Encoding/Decoding circuit. The AL table has been experimentally validated for different sets of CAM and RAM word contents as well as for different CAM and RAM row interconnect settings at 10Gb/s, revealing a power penalty of around 9 dB at a bit-error-rate (BER) of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> . Furthermore, we demonstrate experimental results of a fully integrated InP-based optical CAM cell, which includes an integrated XGM Flip-Flop (FF) memory cell and a Mach-Zehnder Interferometer (MZI) XNOR Access Gate (AG) and supports content addressing operation at 5 Gb/s. This fully-integrated optical CAM cell indicates a possible integration roadmap for the AL constituent building blocks towards the deployment of integrated optical ALs that can be utilized in optical routing or, more general, in optical content matching and forwarding operations.

An efficient reusable attribute-based signature scheme for mobile services with multi access policies in fog computing

Fog computing is an emergent computing paradigm that supports the mobility and geographic distribution of Internet of Things (IoT) nodes and delivers context-aware applications with low latency to end-users. In fog computing, the critical obstacle restricting widespread deployment is security and privacy, especially how to build a lightweight fine-grained message authentication scheme in fog computing. In this paper, we first propose and give the formalization definition to a new variant of the attribute-based signature primitive (ABS), which we called Verifier-Policy Attribute-based Signature (VP-ABS). Distinct from the traditional ABS, in our VP-ABS primitive, the signature generated by the signer is decoupled with the access policy, which means the signer can generate a signature associated with some of his own attributes. Therefore, our VP-ABS can be reusable for multiple access policies. Then we also give a concrete VP-ABS construction over Type-3 pairing under Linear Secret Sharing Scheme (LSSS) policy which supports both AND and OR access gates. In addition, we rigorously prove our VP-ABS scheme is existentially unforgeable in the selective policy model under the adaptive chosen message attack (sP-EUF-CMA). Next, we give the feature comparison and theoretical analysis to our VP-ABS scheme as well as some other representative attribute authentication schemes to show the comprehensiveness of our scheme. To prove the correctness of the theoretical analysis and test the actual performance, we also do simulation experiments. Finally, we use our VP-ABS scheme to build an attribute-based fine-grained message authentication scheme for fog nodes in mobile microservices architecture with multiple access policies.

Electrical Control of Spin Hall Effect in Pt by Hydrogen Ion Adsorption and Desorption.

The manipulation of charge-to-spin current conversion and spin-orbit torque (SOT) is of great interest due to its profound physics and potential applications. Controlling the spin current through the electric field provides a perspective for highly efficient SOT devices. Here, we use H2O-doped ionic liquid gating to realize the reversible and nonvolatile manipulation of the spin Hall effect of Pt, and the spin Hall angle can be modulated by 48% within an accessible gate voltage range. The increase in the spin Hall angle is demonstrated to be caused by the adsorption of hydrogen ions on the Pt surface and the consequent enhancement of the spin Hall conductivity under positive voltage. Furthermore, the enhancement of the spin Hall angle is beneficial to reduce the critical current density for driving the domain wall motion. These results supply a method for the dynamic control of the charge-to-spin current conversion, which will promote the development of spintronic devices driven by electric fields.

Mais espaço, por favor: adaptações espaciais (reformas) e o impacto na habitabilidade de Habitações Sociais

Abstract Social House (SH) residents usually make spatial adaptations. With no technical guidance, these modifications often compromise building performance. This article investigates the dynamics of modifications made to low-income houses and their consequences for habitability conditions. The data were obtained through on-site spatial mapping and a semi-structured interview. The study found modifications that expand the built area and a tendency to occupy the total area of the lot. The type of expansion with the greatest impact on the environmental quality of a house was predominant in the row houses (89.2%). The need for more space is confirmed by houses that have grown more than 30.0% up to over 70.0%. The study also identified a large number of removed windows, and expansions that confined rooms. Besides thermal discomfort, many rooms bear signs of unhealthiness, such as mold, lack of ventilation and sunlight, which have a negative impact on residents’ health. Extreme cases were found (G=12.1%), in which the access gate to the house is the only way of contact with the outside. Spatial adaptations in SH are recurrent and cannot be disregarded as they significantly compromise the health conditions in the houses under study.

5‐3: A Random Access Gate Driver Using a‐IGZO TFTs for External Compensation of High‐Resolution, High‐Frame‐Rate AMOLEDs

The external compensation of AMOLED pixels that is regarded as essential for large‐area displays needs a random access gate driver to select any gate line in vertical blank time. Also, for high‐resolution, high‐frame‐rate, and large‐area displays, a gate driver with overlap driving is needed for high pixel charging ratio. In this study, a decoder‐based random access gate driver with overlap driving is proposed and verified by HSPICE simulation and fabrication of the circuits with a‐IGZO TFTs. The proposed decoder composed of TFTs in parallel enables the random access and overlap driving without increase in circuit area and power consumption.

Access gate-related lower limb fractures in children and adolescents: a review of injury patterns and evaluation of associated injuries

BACKGROUND: Lower limb fractures occurring in and around the home environment and caused by collapsing access gates present frequently to our emergency unit. There is currently limited literature evaluating injuries resulting from access gate accidents. The aim of this study was to evaluate the patterns of lower limb fractures, management options offered and concomitant injuries in children as well as adolescents presenting with access gate-related lower limb traumas. METHODS: A retrospective cross-sectional review of 43 children with 46 lower limb fractures was conducted between 1 January 2017 and 31 December 2020. Hospital records and radiology archives of all children and adolescents under 12 years of age (24 males and 8 females) with lower limb fractures sustained following an access gate injury were reviewed and included for analysis. Data was analysed descriptively using SAS (SAS Institute Inc, Carey, NC, USA), Release 9.4. RESULTS: The prevalence of access gate-related injuries for all lower limb fractures in children and adolescents treated during the four-year period was 11%. The findings revealed that femur fractures are more common, accounting for 50.0% of the cases. The majority of cases were of patients younger than 6 years (71.9%), and predominantly affecting males (3:1). The fractures occurred in a home environment and were commonly related to non-motorised gates, in 93.8% of cases. The oblique fracture patterns comprised 40.6% of the fractures, and 68.8% of the fractures were located in the diaphysis. Open fractures constituted 50.0% of the tibia fractures. Mild head injuries associated with lower limb fractures were observed in 12.5% of the cases. CONCLUSION: The results demonstrated the prevalence of lower limb fractures above all injuries related to access gates. The majority of the injuries observed in this study occurred in manually operated gates, and commonly affected younger patients. In light of these findings, further studies are required into the reasons for these injuries and preventative measures Level of evidence: Level 4.

Valence, Arousal, and Gender Effect on Olfactory Cortical Network Connectivity: A Study Using Dynamic Causal Modeling for EEG

The cortical network including the piriform (PC), orbitofrontal (OFC), and entorhinal (EC) cortices allows the complex processing of behavioral, cognitive, and context-related odor information and represents an access gate to the subcortical limbic regions. Among the several factors that influence odor processing, their hedonic content and gender differences play a relevant role. Here, we investigated how these factors influence EEG effective connectivity among the mentioned brain regions during emotional olfactory stimuli. To this aim, we acquired EEG data from twenty-one healthy volunteers, during a passive odor task of odorants with different valence. We used Dynamic Causal Modeling (DCM) for EEG and Parametric Empirical Bayes (PEB) to investigate the modulatory effects of odors’ valence on the connectivity strengths of the PC-EC-OFC network. Moreover, we controlled for the influence of arousal and gender on such modulatory effects. Our results highlighted the relevant role of the forward and backward PC-EC connections in odor’s brain processing. On the one hand, the EC-to-PC connection was inhibited by both pleasant and unpleasant odors, but not by the neutral one. On the other hand, the PC-to-EC forward connection was found to be modulated (posterior probability (Pp)>0.95) by the arousal level associated with an unpleasant odor. Finally, the whole network dynamics showed several significant gender-related differences (Pp>0.95) suggesting a better ability in odor discrimination for the female gender.

Control Ports Authorities’ Equipment Based on RFID and SQL Security System

Equipment surveillance or tracking is a hard-to-accomplish mission for a multi-locations company. This study examines a complete security system in Alexandria and EL-Dekheila ports of Egypt, as case study, to track equipment location. The system uses RFID (radio frequency identification) and Arduino kit as hardware to detect equipment motion, and visual studio and SQL (structured query language) as software to produce reports. The original place of equipment is saved as a reference. IR and RFID sensors are used at every department’s gate for IT access and for detecting and decoding the received equipment’s RFID card and ID data. Visual studio and SQL help in issuing the report on each equipment’s location and movement time. The system sends instant email messages and cellular phone messages to the control room.

Analysis of the visibility and signal strength of the LoRaWAN network in an urbanized area – a case study of the Bielany campus at the Nicolaus Copernicus University in Toruń

Abstract In order to assess or determine the overall quality of the surrounding geographical environment, it is necessary to measure selected factors that directly or indirectly affect its condition. The aspects to be monitored include i.a. air pollution levels, surface water purity, soil erosion rates, as well as night sky light pollution, a phenomenon increasingly often observed with the unaided eye. To collect data on the night sky brightness on a regular basis, a remote measuring device was designed and constructed using specialised electronic components, wireless communication, programming code, a high-sensitivity digital light data logger and custom-made programme code. LPWAN networks, including LoRa technology, were developed to support a number of mobile devices where long wireless operation is a priority. To determine the potential use of LoRa technology, as well as to plan the target locations of network access gates (gateways) and the deployment of measuring devices for the collection of environmental data, tests of signal coverage and signal visibility, including measurements of its strength, were carried out in a selected, compact part of the city of Toruń. The paper presents the results of research on the visibility of the LoRa network in a built-up area, such as a university campus, using antennas of two different lengths. The obtained results can be used to design distributed measurement networks in areas with varying density of buildings.

An evaluation of airport service experience: An identification of service improvement opportunities based on topic modeling and sentiment analysis

With the increase in airport alternatives and airport service variation, passengers' perception of the airport experience has changed. By working with consumer experience through customer reviews, this study aims to define customer experiences and expectations. Topic modeling and sentiment analysis are applied to 1224 passengers' comments on the top 10 airports collected from Skytrax. Ten topics consisting of baggage claim, immigration process, access gates, procedures at the airport, leisure activities, employee service, transfer/transit amenities, terminal facilities, passport control, ambient conditions are identified. With a few exceptions, positive sentiments have been obtained for these topics. Finally, managerial implications and limitations are shared.

Optical RAM Row With 20 Gb/s Optical Word Read/Write

During the past years, optical memories have emerged as the main way to enable fast access times and increased memory bandwidth in synergy with optical interconnections. The migration, however, to fully functional and practical optical RAMs and cache memories will require an additional yet essential step: Optical memories have to get organized into an optical memory subsystem for delivering seamless cooperation between storage and peripheral decoding units, exploiting also the wavelength dimension for efficient RAM architectural layouts. In this paper we demonstrate the first experimentally verified Wavelength Division Multiplexing (WDM) -enabled optical RAM Row subsystem comprising both the peripheral decoding circuitry and a 4-bit optical RAM Row for storing 20Gb/s 4-bit WDM-formatted optical data words. The proposed scheme comprises a single shared multi-λ Semiconductor Optical Amplifier Mach-Zehnder Interferometer (SOA-MZI) Access Gate (AG) for granting access-control to the complete RAM Row, a passive Column Decoder (CD) that directs the incoming WDM-formatted data words to the respective RAM cells that are in turn based on four broadband Indium Phosphide (InP) photonic integrated Flip-Flops (FFs). Our experimental verification firstly investigates the broadband capability of the elementary InP monolithic RAM cell at 5 Gb/s, revealing error-free Write functionality with <4.5 dB power penalty across the whole C-band confirming in this way the potential of efficient scaling to multi-cell WDM-enabled RAMs. Then, experimental validation of the complete 4-bit WDM-enabled optical RAM Row with 20 Gb/s WDM-formatted data words is performed, featuring simultaneous Access gating, decoding and storage operation for all four RAM cells, having a peak power penalty within the range of [4.6-5.6] dB for Write and [2.2-2.9] dB for Read functionalities, respectively, at a Bit Error Rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> .

Investigating cow-calf contact in a cow-driven system: performance of cow and calf.

In this research communication we describe the performance of dairy cow-calf pairs in two cow-driven CCC-systems differing in cows' access to the calves through computer-controlled access gates (smart gates, SG). We investigated cows' machine milk yield in the automatic milking system (AMS), calf growth, and intake of supplemental milk and concentrate. Two groups each with four cow-calf pairs were housed in a system with a cow area, a calf creep and a meeting area. SG's controlled cow traffic between the meeting area and the cow area where cows could obtain feed, cubicles and the AMS. Calves had ad libitum access to supplemental milk and concentrate. During the suckling phase of 31 d, cow access to the meeting area was free 24 h/d (group 1) or restricted (group 2) based on milking permission. Following the suckling phase, cow access was gradually decreased over 9 d (separation phase). During the suckling phase, cows' machine milk yield (mean ± sd) in the AMS was 11.4 ± 6.38 kg/d. In the separation phase, the yield increased to 25.0 ± 10.37 kg/d. Calf average daily gain (ADG) was high during the suckling phase: 1.2 ± 0.74 kg. During the separation phase, ADG decreased to 0.4 ± 0.72 kg which may be related to a low intake of supplemental milk. Calves' concentrate intake increased with age, and all calves consumed >1 kg/d after separation. We conclude that cows nurse the calf in a cow-directed CCC system well resulting in high ADG, and AMS milk yields were, at least, partially maintained during the suckling phase. Although the AMS yields increased in response to separation, calf ADG was decreased. A low sample size limits interpretation beyond description but provides a basis for hypotheses regarding future research into CCC-systems.

Investigating cow-calf contact in cow-driven systems: behaviour of the dairy cow and calf.

Research is needed on how technology can facilitate cow-calf contact (CCC). This research communication describes the behaviour of dairy cow-calf pairs in two cow-driven CCC-systems differing in cows' access to the calves through computer-controlled access gates (smart gates, SG). Specifically, cow traffic through SG when visiting their calves, allogrooming, suckling and cross-suckling, cows' eating and resting behaviour and finally vocal response to separation were assessed. After 3 d in an individual calving pen, pairs (n = 8) were moved to the CCC compartment with a cow area, a calf creep and a meeting area. During the next 31 d calves could suckle the cows whenever they visited the meeting area (suckling phase). Cows had free (group 1, n = 4 pairs) or restricted access to the calves based on previous activity in the automatic milking system (group 2, n = 4 pairs). SG's controlled cow traffic between the meeting area and the cow area, in which the cows could access resources such as feed, cubicles, and the automatic milking system. Following the suckling phase cow access into the meeting area was gradually decreased over 9 d (separation phase). During the suckling phase, cows paid frequent and short visits to their calves. Pairs spent in total approximately one h/d suckling and allogrooming. However, the duration and frequencies of these events varied among pairs and groups, as did the vocal response to separation. Restricted access - cows performed more (unrewarded) attempts to visit the calves who cross-suckled more. Collectively, free access to the calves may have been more intuitive and welfare friendly. Although a low sample size limits interpretation beyond description and enabling hypothesis formulation for future research, the results indicate that the cow is motivated to visit her calf, albeit through a SG, thus facilitating particular behaviours for which cow-calf pairs are highly motivated.

MOBILE ACCESS CONTROL SYSTEM BASED ON RFID TAGS AND FACIAL INFORMATION

Better access control system security comes at a higher price. It many cases the price is too high for small companies, leaving them vulnerable with cheap and insecure systems. In this work we introduce an alternative access control scheme, which improves access control security while lowering the cost. In the proposed model, passive RFID tags are mounted near a turnstile or a smart door. Tag reading and programming is done via NFC chip directly on the users smartphone. To enhance security, together with smartphone-based authorization we require the user to provide his photograph while entering a secure gate. The photograph is then displayed on a monitoring dashboard side-by-side with the registration picture, so that the two can be matched against each other. The developed client-server application offers administrative system used to configure gate access policies and monitor entrances with filters by access time, user and gate. Also, we propose a mobile application that allows gate registration and serves as a door unlock key. The suggested access control model reduces installation costs required, while maintaining good security. The system is fully wireless and uses cheap autonomous RFID-tags as its main component. We hope, that the proposed system architecture will find its application in small to medium-sized companies.